Apparatus for operating a spark ignition engine on two fuels



June 2, 1970 Ko J. VERLINDE APPARATUS FOR OPERATING A SPARK IGNITION ENGINE ON TWO FUELS Filed Aug. 11, 1967 annulla.

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United States Patent O 3,515,106 APPARATUS FOR OPERATING A SPARK IGNITION ENGINE N TWO FUELS Ko J. Verlinde, Hogere Technische School, Vlissingen, Netherlands Filed Aug. 11, 1967, Ser. No. 660,109 Int. Cl. F02m 1/16 U.S. Cl. 123-127 3 Claims ABSTRACT 0F THE DISCLOSURE Disclosed herein is a method and apparatus for operating a spark ignition engine on dual fuels. A volatile fuel such as gasoline is supplied to the engine carburetor for engine starting and low speed operation. A less volatile fuel such as kerosene is supplied to the carburetor for continuous operation at higher speeds. The dual fuels are supplied from independent supply tanks. The supply of volatile fuel is progressively decreased with increase in engine speed lby closing the volatile fuel supply by compressing a section of the volatile fuel supply conduit by a cam follower which is actuated by the throttle control.

BACKGROUND OF INVENTION The invention relates to t-wo and four cycle spark ignition internal combustion engines and particularly to the use of two fuels to operate such engines.

SUMMARY OF INVENTION -The invention provides a method and apparatus for operating a spark ignition engine on two fuels utilizing a volatile fuel such as gasoline for engine starting and W speed operation and a less volatile fuel such as kerosene for continuous operation at higher speeds. The dual fuels are introduced in the carburetor mixing chamber through separate jets or nozzles, the gasoline being introduced into the low speed nozzle from a separate remote tank and the kerosene being introduced through a high speed nozzle from an additional remote supply or tank.

A control for the volatile fuel supply progressively decreases the introduction of the volatile fuel through the low speed nozzle with increase in engine speed as the engine throttle is advanced. When a wide open throttle condition is attained, the gasoline supply conduit is completely closed. Although various means can be employed, in the disclosed construction the control for varying and closing the volatile fuel supply includes a cam follower or roller which is moved by the throttle control. As the engine speed is increased by actuating the throttle control, the cam follower pinches a compressible section of the gasoline supply conduit against an anvil. The cam follower also controls the shutter in the carburetor through a linkage.

The method and apparatus for operating the engine of the invention with dual fuels minimizes the overall cost of operation through the use of low grade inexpensive fuel such as kerosene. It is particularly suited for use in countries where distillate known as rmotor kerosene is available.

DRAWINGS FIG. 1 is a fragmentary sectional view of an engine and carburetor in accordance with the invention.

FIG. 2 is a fragmentary View of the control for the volatile fuel supply, the control being shown in a closed position.

DETAILED DESCRIPTION Referring to the drawings, there is shown in FIG. l a fragmentary View of a spark ignition engine which is generally designated 10 and which also includes a portion of an engine block 12, a portion of a flywheel 14 and a carburetor 16. The carburetor 16 includes a choke shutter or valve 18 and a throttle shutter or valve 20. The carburetor also includes a first jet, or high speed nozzle 22 for introducing fuel into the venturi 27, and a second jet or low speed nozzle or orifice 24 for introducing fuel into a mixing chamber 26 adjacent the low speed orifice.

In accordance with the invention means are provided for supplying a first fuel of low volatility such as motor kerosene to the first nozzle 22. As used herein a fuel of low volatility refers to a fuel which is not capable of starting the engine and which will not satisfactorily sustain idling operation of a spark ignition internal combustion engine of either the two stroke or four stroke engine type, but which will satisfactorily sustain operation at speeds higher than idling speeds. The means for supplying a first fuel includes a float chamber 28 and a fuel pump 30 adapted to be connected to a remote fuel tank not shown. The remote fuel tank can be pressurized by crankcase pressure or by the fuel pump 30. The fuel pump 30 is connected to the float chamber by a conduit 31.

In accordance with the invention means are provided for supplying to the second nozzle 24 a second and more volatile fuel than the first fuel, as for instance gasoline which is capa-ble of engine starting and engine running operation at all speeds. This means also includes a oat chamber -42 and a fuel pump 44 having a conduit 45 adapted to be connected to a remote fuel tank, not shown. The float chamber is connected to the second jet 24 by conduit 34. A conduit 43 connects the float chamber 42 to the fuel pump 44.

In accordance with the invention means are provided for adjustably inversely varying the rate of supply of the first and second fuels. Such means is operable to decrease the supply of the second fuel to the second nozzle as the rate of supply of the first fuel to the first nozzle increases. More specifically, the supply of the first fuel or kerosene is increased as the throttle is advanced to increase engine speed and the supply of the second fuel or gasoline is progressively decreased with advance of the throttle. More specifically, valve means connected to the throttle linkage are provided for progressively closing the conduit 34 upon increase in the throttle setting, i.e., opening of the throttle which is effective to draw an increasing amount of fuel from the first nozzle 22. Although various arrangements can be employed, in the disclosed construction the valve means includes a part of the conduit 34 including a compressible section 36 of rubber tubing or the like which is normally open during engine starting and during low engine speed operation and which is closed or pinched by a cam follower 46 which pivots toward an anvil or bracket 48 to compress the section 36 as shown in FIG. 2 in response to throttle movement providing increasing engine speed. The cam follower 46 is moved by a cam plate 50 which moves with the timing plate, not shown, in response to operation of a remote throttle control in accordance with the disclosure of U.S. Pat. 2,906, 251. The cam follower 46 is also used to actuate the throttle shutter 20 in accordance with the disclosure in U.S. Pat. 2,906,251.

In operation, the second or relatively volatile fuel, such as gasoline, is supplied through the second or low speed jet 24 through conduit 34 for engine starting. The throttle shutter 20 will normally be in a practically closed or partially closed position during engine starting and idling operation, thus reducing inward flow of air to the mixing chamber 26. Under such circumstances of low suction in the venturi, no low volatility fuel or very little low volatility fuel is discharged through the main jet or nozzle 22. As the engine speed is increased by opening the throttle shutter 20 through the remote throttle control, the first fuel or fuel of relatively low volatility as compared to the relatively high volatility fuel will be supplied in increasing quantity in response to increased suction through the high speed nozzle 22 and venturi 27 into the mixing chamber 26. When the throttle control has been advanced to eifect an engine speed at less than full throttle,

as for instance 3,500 to 4,000 r.p.m., the fuel mixture may include approximately 80 percent kerosene and 20 percent gasoline. IOnce the cam follower starts compressing section 36 of conduit 34 the second fuel supply will be progressively decreased until a wide open throttle condition is attained and the conduit 34 is completely closed. At a wide open throttle condition the engine is operating solely on the rst fuel or kerosene.

One example of a low volatility fuel which can be used as the -rst fuel has an initial boiling point of approximately 150 degrees C. with 60 percent distillation at 200 degrees C., a iinal boiling point of 260 degrees C., and an octane number of MM 66.5. By way of contrast, gasoline which can be used as the second fuel has approximately an initial boiling point of 35 degrees C. with 50 percent distillation at 100 degrees C., a inal boiling point of 190 degrees C. and an octane number of MM 85.0.

The economy of operation of an internal combustion engine in accordance with the invention is readily apparent. In regions or countries where gasoline is relatively expensive and available in limited quantities, operation of an engine as hereinabove described Will be advantageous.

Existing engines can be modified in accordance with the invention by supplying the rst fuel or kerosene through the existing high speed nozzle and connecting the second fuel supply to the low speed nozzle and closing the otherwise conventional conduit or passage between the high speed nozzle and the low speed nozzle.

Various of the features ofthe invention are set forth in the following claims.

What is claimed is:

1. In a spark ignition engine including a carburetor having a mixing chamber with rst and second fuel nozzles communicating with said mixing chamber, and a throttle shutter and a throttle control connected to said throttle shutter, the improvement in combination therewith comprising means for supplying a iirst fuel to said rst nozzle, means for supplying a second fuel to said second nozzle, and means for adjustably varying the rate of supply of the first fuel and the second fuel to said carburetor, said means for adjustably varying the rate of supply of fuel including a conduit having a compressible section, an anvil underlying a portion of said compressible conduit, a cam follower, a cam surface movable in response to movement of said throttle control and operable to move said cam follower toward said anvil and compress said compressible section of said conduit in response to advance of said throttle control.

2. A carburetor designed to permit use of a volatile fuel for starting and low speed operation and a less volatile fuel for high speed operation, said carburetor comprising a mixing chamber, a combustion air inlet leading to said mixing chamber, a nozzle for volatile fuel opening into said mixing chamber, a nozzle for less volatile fuel opening into said mixing chamber, a throttle valve for determining the speed of engine operation by controlling air flow through said mixing chamber, means for adjusting the throttle valve between substantially closed position and open position, means for controlling volatile fuel flow to the volatile fuel nozzle and including a fuel supply line in operative connection with said volatile fuel nozzle, valve means in said fuel supply line and operable to open and close said line respectively permitting and preventing fuel ilow through said line, and a motion transmitting linkvage connecting said throttle valve to said valve means to gradually close said valve means upon gradual opening of said throttle and to gradually open said valve means upon gradual closing of said throttle.

3. A carburetor according to claim 2 including another fuel supply line in operative connection with said less volatile fuel nozzle and wherein said other fuel line is unimpeded during any throttle valve position.

References Cited UNITED STATES PATENTS 1,470,967 10/ 1923 French 123-127 2,059,334 11/ 1936 Gustafsson 123--127 2,115,634 4/1938 Kiesel 123--127 FOREIGN PATENTS 176,118 2/ 1922 Great Britain.

363,397 12/ 1931 Great Britain.

519,591 4/ 1940 Great Britain.

646,412 11/ 1950 Great Britain.

AL LAWRENCE SMITH, Primary Examiner U.S. Cl. X.R. 123-98, 108, 180 

